1. Field of the Invention
The present invention relates to a multiple reciprocating pump suitable for use in, for example, a powered atomizer for spraying and atomizing a chemical liquid. More particularly, the present invention is concerned with a multiple reciprocating pump which can have an increased capacity or displacement without an accompanying increase in size.
2. Description of the Related Art
Multiple piston pumps, suitable for use in powered atomizers for spraying and atomizing chemical liquids or rinsing water are known, for example, as disclosed in Japanese Utility Model Laid-Open No. 60-73885 and Japanese Utility Model Publication No. 63-39429. In such a multiple piston pump, a plurality of piston rods of an equal length are arranged in parallel on the same side of a crankshaft and a plurality of pump chambers are arranged in a row on the same side of the crankshaft as the piston rods. The pistons carried by the piston rods reciprocate in the respective pump chambers so as to increase and decrease the volumes of the pump chambers.
In this known multiple piston pump, the cross-sectional areas of the pump chamber and the piston are undesirably limited by the spacing of piston rods and by the thickness of the partition wall between adjacent piston rods. Thus, it is difficult to design the pump with large cross-sectional areas of the pump chamber and the piston respectively. In other words, in order to increase the capacity or displacement of the multiple piston pump by increasing the cross-sectional areas of the piston chamber and the piston, it is necessary to increase the spacing of the pistons, resulting in an increase in the size of the whole piston pump. It would be possible to increase the capacity of the multiple piston pump by increasing the speed of rotation of the crankshaft. In such a case, however, the pistons, cylinders and seals of the pump would be worn down very quickly.